In particular, the present invention will be discussed with respect to fence systems having electric fence energisers, although it may be possible that aspects of the present invention could be applied to other situations.
Electric fence energisers emit a high voltage pulse approximately every second. The `intensity` of the pulse is such that it acts to deter stock from touching the electric fence.
Typically, an electric fence energiser supplies pulses to electric fences covering a very broad area of a farm. If the farmer is moving stock, has temporary electric fence lines or for some other reason wishes to turn off the electric fence energiser, then he/she usually has to walk a considerable distance to turn off the electric fence energiser or to turn the energiser back on.
A product was invented (which is the subject matter of U.S. Pat. No. 4,270,735) that applied a DC signal to the electric fence line by connecting a battery from the fence to ground. The signal was received by a device that turned the energiser off or on. Unfortunately, this device had many problems. For example the operation of the device was such that there was a large drain on the batteries used in the device to send the signal.
Poor electrical connections commonly occur on an electric fence, e.g. line clamps. Because of these poor connections, often the emitted signal would not reach the energiser switching device.
A further problem was that once the power supply was disconnected from the electric fence energiser, there was a significant start up time from when the electric fence energiser was turned on and the energy storage capacitor becoming sufficiently charged for normal energiser operation.
Further, the above device required a separate control device to the electric fence energiser. This totally separate device connected and disconnected the power supply to the energiser. The cost in labour required in producing the separate device was also a detriment commercially.
There are also other problems associated with attempting to send signals along an electric fence line. One such problem is that it is common for an electric fence line to have induced on it signals from other electric fences, power lines and the like. Often there is attenuation of a signal down the line as well.
It is an object of the present invention to address the above problems, or at least to provide the public with a useful choice.
Further objects and advantages of the present invention will become apparent from the following description which is given by way of example only.